Wireless Monitoring and Control for the Digital Oilfield

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Case Studies

Case Studies

ADCO

Abu Dhabi Company for Onshore Oil Operations (ADCO) approached Wireless Measurement to tackle the problem of monitoring production on a sample of six oil wells located in the Arabian Desert.

The wells were selected close to the edge of the field in the vicinity of water injection wells, used to maintain reservoir pressure. On occasions water break-through had given rise to the need for costly maintenance procedures resulting from inefficient production and increased corrosion. The selected wells are free-flowing and are located in soft desert sand. There is no electrical power supply on site or close by so the solution needed to be self-powered. The soft sand, combined with the need to carry out regular (3-5 year) work-overs, rendered impractical laying any cables from the wellhead to an instrument cabinet.

The installation of wireless pressure and temperature sensors on the wells, combined with real time data transmission to a web based server now enables the operator to view the well performance in real-time. Warnings and errors are flagged up so that an appropriate and immediate response can be made. On one of the wells a solar powered Cathodic Protection system is also connected enabling hourly performance reports in place of the monthly reports previously only obtained by a field visit.

The installation for ADCO made use of the existing GSM network which covers the desert field using an open GPRS connection to the server for continuous real time feed of measurements. The network was also used for distribution of SMS messages to field workers. The system comprised a number of wireless combined pressure and temperature sensors, GPRS based WellSite Controllers (with a solar power suply with backup for night time operation) and the Server based Server hosted on ADCO’s own IT infrastructure. In addition a programmable low power radio interface was added to an existing Cathodic Protection system to demonstrate the capability of the system to interface to proprietary, as well as standards based, third party equipment.

The system has been in continuous operation in the field since April 2009. During this time there has been no field equipment failure and, on only a handful of occasions, has field equipment needed to be reset for any reason. After 11 months’ operation, one sample sensor was temporarily removed for inspection and to check its calibration against a pressure reference. The sensor was found to be measuring within 0.5% as per original specification with no adjustment necessary. The server software has been upgraded with user interface changes requested by the client and has had some periods of down time due to hardware and IT hosting issues. In any large scale deployment the software would be installed on multiple servers with redundancy and automatic failover.

These periods of downtime have served to demonstrate the effectiveness of the automatic data retrieval from the inbuilt data logging capability of the sensors. Overall system was measured after the first six months’ operation. Since each sensor was reporting a pair of measurements every 2 minutes, a total of 7.8M readings could have been recorded in the database. Of this total potential data, the system had captured 98.7%.

The potential savings associated with deploying this technology more widely have been analysed as follows: The present practice of monitoring wells by visual inspection every 2-3 days means that any shut-in caused by over/under pressure or accidental trip may go undetected for up to 3 days. The cost in deferred production averages at about 1½ days, or 3-4,000 bbl per incident.Since unplanned shut-in events take place on average at least twice per year, this equates to a 1% effective capacity increase. In today’s market these losses are accommodated in the margin between agreed production quotas and overall production capacity. Remote monitoring of three critical parameters – hydraulic control pressure, annulus pressure and chemical injection tank levels – would reduce total field visits by one third. Not only is this a major cost saving, but it also represents a major improvement in exposure of personnel to health and safety hazards associated with desert travel and field visits.

The Cathodic Protection units are visited every two months for data to be downloaded using a laptop for analysis back in the field office. The control panels are frequently inaccessible due to sand build up blocking the enclosure door. When this happens, another team is called to clear the sand before a third site visit can be carried out to finally access the data. Once retrieved, the data is analysed. Any problem or failure of the system may be up to 60 days earlier resulting in unnecessary corrosion of the protected asset.

In evaluating Wireless Measurement’s remote monitoring capability in the hostile environment of the Arabian Desert, ADCO have concluded that the system is both robust, reliable and that the instruments maintain excellent accuracy. The remote monitoring capability reduces the number of necessary field visits which carries both a substantial financial saving and reductionin exposure of workforce to risk. A substantial increase in Effective Production Capacity yields potential increased in revenue. The ability to respond to events in real time reduces risk to assets and enables losses or equipment damage to be minimised.

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Monitoring production parameters from oil wells located in remote and hostile environment has enabled the operator to reduce deferred production, cut down on regular inspection visits and gain a much better understanding of well performance. Real-time alarms enable an immediate response to potentially costly changes in production parameters.

ADCO have concluded that the system is both robust, reliable and that the instruments maintain excellent accuracy.